There are now several clamping apparatuses presently used in association with band heaters. One common clamping apparatus is a screw and nut arrangement as generally shown in FIG. 1 wherein a screw and nut is used to tighten and hold the clamping strap to an object. The screw and nut arrangement possesses numerous disadvantages or deficiencies, namely: (1) the male screw is hard to start into the female nut on a hot plastic extruding and injection molding machine; (2) the screw and nut arrangement has a high profile which requires clearance around the clamping strap; (3) the screw and nut arrangement provides little flexibility to maintain tension on the clamping strap if and when thermal expansion causes the strap and cylinder diameters to change relative to each other; and (4) the screw and nut arrangement is relatively expensive when compared to the arrangement of the present invention. Another common clamping apparatus is a spring clamp arrangement as generally depicted in FIG. 2. The principal disadvantages or deficiencies of the spring clamp arrangement are: (1) the clamp has a high profile which requires clearance around the clamping strap; and (2) the spring clamp arrangement is quite expensive when compared to the arrangement of the present invention. Another clamping apparatus is a wedge arrangement wherein a sheet metal wedge having two tapered flanges fits over the ears formed on the clamping strap for moving the ears towards each other, as generally shown in FIG. 3. The wedge arrangement also possesses numerous disadvantages or deficiencies, namely: (1) the sheet metal wedge can easily become loose and work its way off of the ears of the clamping strap; (2) the wedge arrangement provides no flexibility to maintain tension on the strap when thermal expansion causes the diameters of the clamping strap and cylinder to change relative to each other; and (3) the wedge arrangement is very expensive when compared to the arrangement of the present invention.
Numerous patents disclose clamping straps useful for numerous applications as exemplified by the following U.S. Pat. No. 583,454 to Burns; U.S. Pat. No. 1,559,049 to Rutledge; U.S. Pat. No. 1,709,743 to Sagenkahn et al.; U.S. Pat. No. 2,101,586 to Leach; U.S. Pat. No. 4,183,120 to Thorne; U.S. Pat. No. 4,483,556 to Li Volsi; U.S. Pat. No. 4,557,024 to Roberts et al.; U.S. Pat. No. 5,172,879 to Calmettes et al; and U.S. Pat. No. 5,359,179 to Desloge et al.
The Desloge patent discloses a band and strip heater for heating barrels and nozzles of plastic extruding and injection molding machine which incorporates a screw and nut clamping arrangement as generally depicted in FIG. 1 for maintaining intimate contact between the heater and the cylindrical surface to be heated. The Sagenkahn et al patent discloses a generally cylindrical clamping strap having a first end tab or ear with an opening therein, a second end tab or ear with an opening therein, and a latch mechanism having ratchet teeth on one of its edges. In operation, the clamping strap of Sagenkahn et al is tightly secured about a cylindrical member by thrusting the latch mechanism into the openings in the first and second end tabs or ears to cause the ratchet teeth to ride over the walls of the openings to lock the clamping strap onto the cylindrical member. The Leach patent discloses several embodiments of a clamping strap, with the embodiment disclosed in FIGS. 4 and 5 being somewhat pertinent to the present invention. Leach, in FIGS. 4 and 5, discloses a generally cylindrical clamping strap including a first arcuate section having a reduced, closed, end portion with a plurality of ratchet teeth along its side edges and a cutout separating the side edges; and a second arcuate section having an end portion with a generally oblong slot. In operation, the clamping strap of Leach is tightly secured around a cylindrical object by thrusting the reduced end portion of first arcuate section into the generally oblong slot in second arcuate section to cause the ratchet teeth to ride over the side walls of the to lock the clamping strap to the cylindrical body.